Doctor: "If you had even the slightest sense of humor, you'd realize I was making a small joke." Seven: "Very small." This is reminiscent of a scene between Chekov and Spock in Star Trek: The Trouble with Tribbles (1967).
This episode marks the final appearance of the type 3 phaser on Star Trek: Voyager, a form of rifle that was introduced in Star Trek: First Contact. All phaser rifles subsequently shown on the series are the compression phaser rifle.
This episode's title, at three letters, beat the record for the shortest in Star Trek history held by "Miri" for nearly 32 years. It held the record for just three years, when it was beaten by "Q2", which also held it for three years before it was beaten in turn by "E²".
This episode is similar to two other Voyager episodes, "Persistence of Vision" and "Bliss" which feature The Doctor working closely with another crew member (Kes in the former, Seven once again in the latter) while most of the crew is incapacitated in some way.
A holographic version of Torres states that she joined the Maquis after Chakotay saved her life. This was previously established in Jeri Taylor's book Pathways and is the only mention in the series of Torres' motivations for joining the group.
The trivia item below may give away important plot points.
A similar storyline to this occurs in the Star Trek: Enterprise episode "Doctor's Orders", when Doctor Phlox is forced to take control of the ship on his own, to pilot it through a nebula, but begins to hallucinate.